Optionalencoding: stringSends a Request, with automatic HEAD-simulation fallback for
servers that do not support the HEAD method.
Sends a HEAD request, falling back to simulation when the server does
not support HEAD. Tries, in order:
HEAD request via fetch().Range GET to retrieve the first FILE_TYPE_MAGIC_NUMBER_SIZE
bytes (magic-number file header).GET that reads the first FILE_TYPE_MAGIC_NUMBER_SIZE
bytes then cancels the body stream.
Binary data